I thought I’d chime in with a quick review of the F1-T-B.
I’ve been wearing these daily since I got them and so far, I love them. I went with the B variation because for me, they were the most appealing.
I do agree with the earlier reviews that they are heavy, but it doesn’t really bother me. I adjusted the side arms and nose pads to my liking, which helps keep the glasses in place.
The build quality is very good. In comparison, I own a range of sunglasses from Ray Ban, Adidas (Made in Austria), Neighborhood, VISVIM, and Louis Vuitton. I feel like these are more on par with VISVIM in terms of build quality.
I’ve worn mine in the sun and the spill of light through the clip-on lenses did not bother me. In the rain, I took the clip-ons off and used just the yellow tinted lenses. I felt like I was able to see far better wearing these during a typical rainy Vancouver afternoon/evening. It was a pleasant surprise to say the least
Maybe I’m not as critical as the others here who commented on their sunglasses but I feel like these are a great pair of regular clip on sunglasses, albeit slightly overpriced. The only thing that really annoys me is that I need to clean off finger prints twice as often as my other sunglasses. Ok one other gripe I had was that the cleaning cloth they threw in felt badly cut. It was like someone took a dull pair of scissors and unevenly cut out a square.
I can’t see too many folks buying and keeping these unless they are die hard Acronym fans. For me, I’m very happy I grabbed a pair. Cheers!!!

could not agree more. got mine from everyone’s favorite @Xu Jianfeng and have used it almost every day since i got it. the fabric patinas extremely well and remains durable and without any holes to this day first photo is the day i got it and the second is a full year later. can’t sing it’s praises enough.

@501XX4EVER Oh sorry, I never answered your question. Yes of course they have a double-chainstitched outseam
And while we are at it, here is the fit pic of these jeans after they have been hememd to 34" (to allow for some future shrinkage and cuffing).